Security is being tightened at UK airports following fears from the US of increased terrorist threat levels.

The security threat level remains at ‘substantial’, meaning that an attack is a strong possibility. The changes come after the White House voiced fears that terrorists were planning to bring down a plane with help from radicalised European jihadists returning from Syria.

President Barack Obama told American TV news channel ABC: “They’ve got European passports. They don’t need a visa to get into the United States”.

The Department of Transport has issued a statement confirming increased security, but would not provide further information on the details of this.

“We have taken the decision to step up some of our aviation security measures,” it said.

“For obvious reasons we will not be commenting in detail on those changes.”

The majority of passengers should not experience significant disruption, but travellers to the US should arrive earlier to allow for any additional time it takes to get through the extra security checks.

“The safety and security of the public is our paramount concern. The UK has some of the most robust aviation security measures and we will continue to take all the steps necessary to ensure that public safety is maintained,” added the Department of Transport.

The Department of Homeland Security said changes to aviation security in the US would be made in the “upcoming days”. Airlines have responded to say they are ready to bring in any new security measures when instructed.